Dunno, negative forming bucks should work well for case parts, better yet, choose the right fabric or textured surface for lining the negative buck, then blow mold the case part and the outside of the part might approximate a textured Mac.

Reverse plaster casting coupled with some flexible rubber "diamond plate" liner to match a compact's side panel curves for a blow molding seems . . . hrmmm? }

Maybe a clear diamond plate RuggedizedProtoHoaxBook™ . . . ;D

As vacuum forming bucks go, it doesn't get much better than the real glass deal.